The NTSB staff perform the very important functions of investigating transportation accidents, determining probable cause, contributing factors and making safety recommendations to regulatory agencies, manufacturers and operators. That is the charter of the organization. They recommend and it's up to industry and regulators whether to adopt the advice or not.
Were it not this way, just about all transportation systems might be completely impractical and without economic viability. Without the recommendations made by all the various transportation safety organizations, travel would be much less safe than it currently is. After all, a good number of safety initiatives got their impetus from the accident reports and associated recommendations. The balance between safety and performance (economic and capabilities-wise) is actually very good in that progress continues in both of these seemingly opposite imperatives simultaneously. There remain a number of areas where more emphasis is required and the tides shift slowly. The NTSB does not get all it wants and industry must sometimes accept the recommendations when regulatory bodies mandate them. Not a perfect system by any means, but it's the only one we've got. Debating the relative merits of each and every recommendation continues to be the best way forward.